The research in the present proposal is designed to explore the relation between the development of working memory and the development of cognitive structures. Two experiments are proposed to test this relation in adolecence. The first experiment is designed to further clarify the relationship between working memory and cognitive structure by expanding the data base to include new measures of cognitive structures. Case has proposed that increases in working memory are a necessary precondition for increases in cognitive structure. The first study is designed to examine whether this relationship holds when the definition of cognitive structure is broadened to include structures other than those defined within Case's own theory. This study will also examine the causal connection between increases in working memory storage capacity and increases cognitive structure. The second experiment is designed to discriminate those aspects of cognitive structures that are related to working memory increases from those aspects that are not. Do number of units, stage, the type of relation between the units, or all three aspects of a skill structure best relate to increases in working memory capacity? The methodology to be used involves determining working memory by measuring two span tests and determining cognitive structures by assessments suggested by skill theory. The long term objective of the proposed research is to trace the developmental progression of the relationship between information processing characteristics and cognitive structures and to explore a possible bridge between two relatively separate theoretical approaches within psychology. The results of this study will add to our knowledge about cognitive development, an area of knowledge that is implicated in most other developmental fields. The results of this study will add to our understanding of normal development, which serves as a foundation for the identification and evaluation of mental disorders that arise in children and adolescents.